In today's world, people are more and more concerned with the protection of their civil liberties. The proliferation of security cameras in malls, retail stores, gyms, changing rooms, and apartment complex lobbies only serves to heighten their concerns. Fortunately, when monitoring an area for security purposes, technology exists that allows certain parts of the security camera's field of view to be kept private. The ability to “mask” certain areas of a camera's field of view, such as, for example, a window of a house is included in many security camera systems. The areas that are masked off are referred to as “privacy zones”. Wide-area security cameras now provide the ability to mask off privacy zones thus prohibiting certain areas from being monitored and/or recorded. Without privacy zones, security personnel would have the ability to spy on members of the public without their consent.
Analog Pan/Tilt/Zoom (“PTZ”) dome cameras currently include features to mask selected privacy zones in the camera's field of view. In these analog dome cameras, the privacy zone corners are defined by moving the pan-tilt motor until the center of the analog video screen reaches each privacy zone corner. Each corner is then represented by the pan-tilt coordinate where the corner would be at the center of the video screen. However, with the advent of digital Internet Protocol (“IP”) dome cameras, instead of an analog video output, a stream of compressed digital data is used to transfer the camera video images. A graphical user interface such as a browser web page is used to display the video image stream by uncompressing the received digital data. It is desirable to define the privacy zone corners on the browser page using one still video image obtained from the received stream.
However, as the privacy zone corners are drawn on the still video image, methods must be used to convert the drawn points on the planar image to the IP dome camera's pan-tilt-zoom (“PTZ”) motor coordinates, at which these corners would be situated at the substantial center of the video screen. With the pan-tilt coordinates for each privacy zone corner, the PTZ dome camera's privacy zone algorithm must draw the privacy zone coverage areas on the received live video before it is compressed into digital data and streamed. However, there is currently no adequate method and system for converting privacy zone points taken from a captured still video image to their corresponding pan-tilt coordinates.
Therefore, what is needed is a system and method for converting privacy zone points taken from a captured still video image to their corresponding pan-tilt coordinates, which are the coordinates to which PTZ dome camera uses to define the privacy zone.